Characterization of human dental plaque formed on hydrogen-ion-sensitive field-effect transistor electrodes.

The purpose of this study was to evaluate (with scanning electron microscopy and microbiological characterization) the bacterial deposits which accumulate on hydrogen-ion-sensitive field-effect transistor electrodes (pH-ISFET) under conditions normally employed for telemetric monitoring of changes in human dental plaque pH. Electrodes were mounted in a carrier appliance which was worn for two, four, and six days. The plaque pH response to a sucrose solution increased with the age of the plaque, as expected from previous studies. After two days, the electrode was shown to be almost completely covered with cocci. At days 4 and 6 there was a dramatic increase in the number of rods present in the plaque. Adjacent enamel surfaces showed similar accumulations of bacteria. The total number of bacteria which had accumulated per unit area by day 4 was very similar for the electrode and enamel surfaces. On both surfaces the plaque contained approximately 25% streptococci, and the dominant species was Streptococcus sanguis (approximately 75%). The plaque which accumulated on pH-ISFET electrodes could not be distinguished visually or microbiologically from that which formed on control enamel surfaces.

[Factors affecting the serum thyroid hormone concentration during fasting in rats--with special reference to the relation with temperature].

The present studies examine the effect of starvation together with cold or hot exposure on thyroid hormone levels in rats. At 23 degrees C starved for 5 days, serum thyroid hormone levels decreased significantly compared with fed rats, averaging 3.6 +/- 0.5 micrograms/dl of thyroxine (T4), 47 +/- 11 ng/dl of triiodothyronine (T3), 1.4 +/- 0.3 ng/dl of free T4 and 39.6 +/- 5.1 pg/ml of reverse T3, respectively. At 15 degrees C rats starved for 5 days, serum free T4 level significantly more increased than that of 23 degrees C starved rats, while serum T4 level and T3 did not increase significantly. At 30 degrees C rats whether concomitant starvation or not, serum thyroid hormone levels of both group markedly more decreased than control rats. These experiment provide additional evidence that thyroid gland and the peripheral metabolism of thyroid hormone respond to variety situations such as cold or hot exposure together with starvation or not.

[Evaluation of measuring serum trypsin by radioimmunoassay and clinical application for the study on the exocrine function in diabetics (author's transl)].

Measurement of serum concentration of trypsin by RIA-Gnost Trypsin kit (Hoechst-Japan) was evaluated. The clinical usefulness of measuring serum trypsin level in diabetic patients was assessed. The measurement of trypsin using the radioimmunoassay (RIA) kit revealed good precision and reproducibility with intraassay error ranging from 3.6 to 5.5% in C.V. corresponding to mean trypsin concentration of 236.5-838.7 ng/ml and interassay error ranging from 8.1 to 11.1%. Tests for recovery and dilution were satisfactory for clinical use. Clinical materials included 35 normal subjects, 88 diabetics, 22 patients with liver diseases, 3 with acute pancreatitis, 7 with chronic pancreatitis and 3 with chronic renal failure. Serum trypsin concentration in normal controls was 157.6 +/- 59.9 ng/ml (m + 1 S.D.). Diabetic patients treated with diet therapy alone revealed serum trypsin level of 203.6 +/- 74.8 ng/ml (n = 50). In diabetics treated with sulfonil urea serum trypsin was 171.3 +/- 83.0 ng/ml (n = 25). In patients receiving insulin serum trypsin level was 90.5 +/- 49.0 ng/ml (n = 13). In patients with liver diseases, acute pancreatitis, chronic pancreatitis and chronic renal failure serum trypsin concentration were 236.9 +/- 88.0, 520.1 +/- 80.0, 113.0 +/- 75.6, and 2557 +/- 2771 respectively. Our results may indicate impaired pancreatic exocrine function in patients with severe diabetes mellitus. Increased serum trypsin level in diabetics treated with diet therapy may be due to stimulated excretion of trypsin resulted from restricted food intake. However, further study in larger number of patients is needed.